Pourable solid mixture

ABSTRACT

Polymerizable liquid synthetic resins, liquid reactive constituents of synthetic resins or liquid additives for plastics, in each case containing mineral fillers, are converted to dry, pourable mixtures by mixing with 0.25-5% by weight of a crystalline synthetic calcium silicate, which can be in diverse stages of hydration and has a high length/width ratio and width dimensions of less than 1 μm, it being possible, by this means, to employ the resins not only as casting resins but also as compression moulding resins and adhesives. In addition, handling and processability are improved.

The present invention relates to a pourable solid mixture which consistsof a liquid polymerisable synthetic resin, liquid reactive constituentfor a plastic or liquid additive for a plastic, this component beingprovided with mineral fillers, and a crysalline synthetic calciumsilicate.

In industry, spreadable or castable synthetic resins to which specificproperties are imparted by the addition of fillers are frequentlyemployed. In general, the fillers are mixed into the resins only shortlyprior to processing. However, the processing of fillers is subject tosafety regulations, which frequently can no longer be met by theprocessors.

The manufacturers of plastics are therefore increasingly adopting thepractice of adding the fillers to the plastics beforehand andsuppressing sedimentation of these fillers by adding sedimentationinhibitors. However, partial demixing of the solid and liquid componentscannot always be entirely prevented by this means. A great disadvantageof the filled spreading and casting resins is that, because of therelatively high viscosity and the formation of sediments, they presentdifficulties in processing. A particular disadvantage is that theseresins cannot be removed from the containers without leaving anyresidue; this, moreover, applies in the case of many of the materialsused for the preparation and processing of plastics, for example in thecase of liquid additives for plastics or liquid reactive constituentsfor the preparation of plastics, and is regarded as being uneconomicaland can pollute the environment. It is extremely desirable to eliminatethe unsolved problem of virtually complete withdrawal of liquid, filledcomponents or liquid materials for the preparation and processing ofplastics, and this is the object of the present invention.

The present invention relates to a pourable, solid mixture whichcontains, based on the total mixture, (a) 49.75-7.5 and preferably44.7-7.5% by weight of a polymerisable liquid synthetic resin, of aliquid reactive constituent for a plastic or of a liquid additive for aplastic, (b) 50-87.5 and preferably 54.7-87.5% by weight of a mineralfiller and (c) 0.25-5 and preferably 0.6-5% by weight of a crystallinesynthetic calcium silicate, which can be in diverse stages of hydrationand has a high length/width ratio and a width dimension of less than 1μm .

In particular, the mixture contains component (a) in a proportion of35-15% by weight and component (b) in a proportion of 64.4-80% byweight.

Suitable liquid synthetic resins are, for example, those which under theaction of light, heat and/or catalysts can be polymerised duringprocessing to give thermosetting end products. The resins areessentially self-crosslinkable synthetic resins, which in general areprepolymers or pre-adducts.

Examples of self-crosslinkable synthetic resins are: phenoplasts whichare obtained from aldehydes and phenols, which can be alkylated phenols,and are prepared in a basic medium, aminoplasts, for exampleureaformaldehyde resins or melamine-formaldehyde resins, alkyd resinsand oil-modified alkyd resins, unsaturated polyesters, especially basedon maleic acid, epoxide resins, especially based on bisphenol A,polyurethanes, unsaturated polyimides, especially based onbis-maleimides which can be C-alkylated, and silicones.

Suitable expoxide resins are in particular those which have, on average,more than one glycidyl group, β-methylglycidyl group or2,3-epoxycyclopentyl group bonded to a hetero-atom (for example sulfurand preferably oxygen or nitrogen); preferred epoxide resins arebis-(2,3-epoxycyclopentyl)ether; di- and poly-glycidyl ethers ofpolyhydric aliphatic alcohols, such as 1,4-butanediol, or polyalkyleneglycols, such as polypropylene glycols; di- or poly-glycidyl ethers ofcycloaliphatic polyols, such as 2,2-bis-(4-hydroxycyclohexyl)-propane;di- and poly-glycidyl ethers of polyhydric phenols, such as resorcinol,bis-(p-hydroxyphenyl)-methane, 2,2-bis-(p-hydroxyphenyl)-propane(=diomethane), 2,2-bis-(4'-hydroxy-3',5'-dibromophenyl)-propane or1,1,2,2-tetrakis-(p-hydroxyphenyl)-ethane, or of condensation productsof phenols with formaldehyde which are obtained under acid conditions,such as phenol novolacs and cresol novolacs; di- andpoly-(β-methylglycidyl)ethers of the abovementioned polyhydric alcoholsor polyhydric phenols; polyglycidyl esters of polybasic carboxylicacids, such as phthalic acid, terephthalic acid, Δ⁴ -tetrahydrophthalicacid and hexahydrophthalic acid; N-glycidyl derivatives of amines,amides and heterocyclic nitrogen bases, such as N,N-diglycidylaniline,N,N-diglycidyltoluidine orN,N,N',N'-tetraglycidyl-bis-(p-aminophenyl)-methane; triglycidylisocyanurate; N,N'-diglycidylethyleneurea;N,N'-diglycidyl-5,5-dimethyl-hydantoin,N,N'-diglycidyl-5-isopropyl-hydantoin andN,N'-diglycidyl-5,5-dimethyl-6-isopropyl-5,6-dihydrouracil.

Liquid pre-reacted adducts of such epoxide resins with curing agents forepoxide resins are also suitable.

The synthetic resins of component (a), which contain functional groupscan also be reactive constituents of a plastic and be crosslinked withsuitable curing agents or modified with suitable comonomers.

Suitable curing agents for epoxide resins are acid or basic compounds.Examples of suitable curing agents are: amines or amides, such asaliphatic, cycloaliphatic or aromatic primary, secondary and tertiaryamines, for example monoethanolamine, ethylenediamine,hexamethylenediamine, trimethylhexamethylenediamine, diethylenetriamine,triethylenetetramine, tetraethylenepentamine,N,N-dimethylpropylene-1,3-diamine, N,N-diethylpropylene-1,3-diamine,2,2-bis-(4'-aminocyclohexyl)-propane,3,5,5-trimethyl-3-(aminomethyl)-cyclohexylamine ("isophorone-diamine"),Mannich bases, such as 2,4,6-tris-(dimethylaminomethyl)-phenyl;m-phenylenediamine, p-phenylenediamine, bis-(4-aminophenyl)-methane,bis-(4-aminophenyl)-sulfone and m-xylylenediamine; adducts ofacrylonitrile or monoepoxides, such as ethylene oxide or propyleneoxide, with polyalkylenepolyamines, such as diethylenetriamine ortriethylenetetramine; adducts of polyamines, such as diethylenetriamineor triethylenetetramine, in excess, and polyepoxides, such as diomethanepolyglycidyl ethers; ketimines, for example of acetone or methyl ketoneand bis-(p-aminophenyl)-methane; adducts of monophenols or polyphenolsand polyamides; polyamides, especially those obtained from aliphaticpolyamines, such as diethylenetriamine or triethylenetetramine, anddimerised or trimerised unsaturated fatty acids, such as dimerisedlinseed oil fatty acid (VERSAMID); polymeric polysulfides (THIOKOL);dicyandiamide, aniline-formaldehyde resins; polyhydric phenols, forexample resorcinol, 2,2-bis-(4-hydroxyphenyl)-propane orphenol-formaldehyde resins; boron trifluoride and its complexes withorganic compounds, such as BF₃ -ether complexes and BF₃ -aminecomplexes, for example BF₃ -monoethylamine complex; acetoacetaniline-BF₃complex; phosphoric acid; triphenyl phosphite; polybasic carboxylicacids and their anhydrides, for example phthalic anhydride, Δ⁴-tetrahydrophthalic anhydride, hexahydrophthalic anhydride,4-methylhexahydrophthalic anhydride, 3,6-endomethylene-Δ⁴-tetrahydrophthalic anhydride, 4-methyl-3,6-endomethylene-Δ⁴-tetrahydrophthalic anhydride (=methylnadic anhydride),3,4,5,6,7-hexachloro-3,6-endomethylene-Δ⁴ -tetrahydrophthalic anhydride,succinic anhydride, adipic anhydride, trimethyladipic anhydride, azelaicanhydride, sebacic anhydride, maleic anhydride or decenylsuccinicanhydride, pyromellitic acid dianhydride or mixtures of such anhydrides.

Examples of suitable curing agents for polyurethanes and polyisocyanatesare liquid, branched polyesters, linear polyesters, polyacetals,polyethers and polythioethers.

Suitable comonomers, for example for unsaturated polyesters orpolyimides, are, for example, ethylenically unsaturated compounds suchas styrene, acrylic acid esters or methacrylic acid esters.

Furthermore, the reactive constituent for a plastic can be apolymerisable monomer, which monomers are polymerised on their own ortogether with comonomers, for example polyfunctional expoxides andisocyanates or ethylenically unsaturated compounds.

Examples of liquid additives for plastics are polymerisationaccelerators, polymerisation catalysts or polymerisation initiators,reactive diluents, stabilisers against light-induced or heat-induceddegradation, plasticisers, antioxidants, fluorescent brighteners, flameretardants and processing assistants, such as flow improvers or mouldrelease agents.

Examples of accelerators for epoxide resins are tertiary amines andtheir salts or quaternary ammonium compounds, for example2,4,6-tris-(dimethylaminomethyl)phenol, benzyldimethylamine,2-ethyl-4-methyl-imidazole and triamylammonium phenolate; or alkalimetal alcoholates, for example sodium hexanetriolate, mono- orpolyphenols, such as phenol or diomethane, or salicylic acid.

The mineral filler can be: glass, quartz, clay minerals, feldspars,silicates, carbonates, rock powders, alumina or hydrated aluminas,oxides, carbon, carbides or sulfates, and the materials can be syntheticor naturally occurring materials. Examples are: quartz powder, mica,talc, asbestos, slate flour, kaolin, wollastonite, powdered chalk,dolomite, magnesium carbonate, gypsum, barytes, aluminium oxide,bentones, silicic acid aerogel, lithopones, titanium dioxide, carbonblack, graphite, metal oxides, glass powders, glass spheres, glassfibres, zinc sulfide, silicon carbide, cristoballite or a mixture offillers. Quartz powder is preferred.

The fillers can be in fibre form to granular or pulverulent, and can betreated with adhesion promoters which promote binding of the polymer tothe particles of the filler. Finely divided surface-active fillers arepreferred.

The crystalline synthetic calcium silicate contains particles ofelongated shape and can be rod-shaped to acicular. The width dimensionis less than 1 μm and the internal surface area can be up to about 100m² /g. The length/width ratio can be, for example, in the range from10:1 to 200:1. The methods of preparation for synthetic calciumsilicates of this type are known and are carried out on an industrialscale. The methods are hydrothermal reactions, in which lime and quartzsand are reacted with water under pressure at elevated temperatures, andthe ratios can be varied in accordance with the desired end product.

Acicular crystalline xonotlite of the formula Ca₆ [(OH)₂ /Si₆ O₁₇ ] hasproved particularly valuable.

The calcium silicate has to be added only in small amounts in order toachieve solidification of the liquid component (a), which is providedwith fillers. The amount added depends on the type and the amount offiller.

The mixtures according to the invention can be prepared by simple mixingof the components in industrial equipment, such as stirred vessels,known for this purpose. Advantageously, all of the components are addedtogether and the mixture is stirred until it has changed to a solid, dryand pourable material, which usually disintegrates into small crumbs. Itis surprising that even with small amounts of these synthetic calciumsilicates, the liquid to viscous component (a), which is provided withfillers, of the mixture according to the invention can be converted to adry material, which has great industrial advantages with regard tohandling and processing.

All of the filler can be incorporated in a synthetic resin or a reactiveconstituent, homogeneous distribution being maintained since demixingdue to sedimentation can no longer take place. Pourable materials arevery much easier to handle than viscous liquids. They can be removedfrom the containers without the use of auxiliaries, virtually noresidues remaining in the containers, and as a result of this losses andexpensive cleaning operations are avoided. A further advantage is thehigh storage stability of these mixtures according to the invention andthe conversion of liquid casting resin systems into compression mouldingresins, which constitutes an extension of the field of application. Withthe additives, according to the invention, for plastics, easierincorporation and better distribution of the additives in the substrateare achieved. Despite the small amount of synthetic calcium silicateadded, markedly better mechanical properties, for example increasedflexural strength, are, surprisingly, already observed in mouldings madeof cured resins.

The synthetic resins according to the invention can, if desired, afterthe addition of conventional additives such as curing accelerators, beused as compression moulding resins, or, whcn liquefied by the additionof liquid components, for example reactive diluents, or by warming, orby the addition of fusible components, can be used as casting orspreading resins. Mixtures, according to the invention, of reactiveconstituents of plastics, for example an epoxide resin/curing agentmixture, can likewise be employed as compression moulding compositionsand adhesives. Furthermore, it is possible to liquefy these reactiveconstituents with liquid reactants or by warming, to give casting orspreading resins. A further possible application is the preparation ofcompositions, which are relatively stable on storage, from reactiveconstituents, accordng to the invention, of synthetic resins, such asresin/curing agent or resin/curing accelerator. The possibility ofreactions at the boundary surface between the resin and the curing agentcomponent does indeed prevent unlimited storage, but the storagestability is sufficient to supply one-component systems to processingcompanies, which is particularly advantageous. The mixtures according tothe invention can be liquefied under pressure and therefore can also beprocessed by the cold-press process.

The examples which follow illustrate the invention in more detail.

EXAMPLE 1

Preparation of a solid, pourable resin component from a liquid resin

100 g of diglycidyl hexahydrophthalate (epoxide content: 5.5-6.3equivalent/kg), 126 g of extremely fine quartz powder, 210 g of quartzpowder and 12 g of synthetic calcium silicate (xonotlite) are weighedtogether at room temperature into a tinplate box and mixed at roomtemperature for about 1 minute at 1,300 rpm with a paddle stirrer.Pourable crumbs about 2 mm in diameter form.

A sample of this dry material is stored in a glass bottle with a screwtop in a drying cabinet at 60° C. for 6 months. No caking takes place.

The entire contents can be emptied out by simply pouring out.

EXAMPLE 2

Preparation of a solid, pourable curing component from a liquid curingagent

100 g of isomerised methyltetrahydrophthalic anhydride with a viscosityof 50 to 100 cP at 25° C. 305 g of quartz powder, 140 g of extremelyfine quartz powder and 7.1 g of synthetic calcium silicate (xonotlite)are weighed together at room temperature into a tinplate box and mixedat room temperature for about 1 minute at 1,300 rpm with a paddlestirrer. A pourable powder containing crumbs 2 to 4 mm in size forms.

A sample of this dry material is stored in a glass bottle with a screwtop in a drying cabinet at 60° C. for 6 months. No caking takes place.

The entire contents can be emptied out by simply pouring out.

EXAMPLE 3

Preparation of a dry, pourable accelerator from a liquid accelerator

100 g of a curing accelerator consisting of polypropylene glycol 425which contains about 2% by weight of the corresponding sodiumalcoholate, 200 g of quartz powder, 160 g of extremely fine quartzpowder and 16 g of synthetic calcium silicate (xonotlite) are weighedtogether at room temperature into a tinplate box and mixed at roomtemperature for about 1 minute at 1,300 rpm with a paddle stirrer. Apourable powder forms.

A sample of this dry material is stored in a glass bottle with a screwtop in a drying cabinet at 60° C. for 6 months.

The entire contents can be emptied out by simply pouring out.

EXAMPLE 4

Preparation of a pourable mixture from a liquid epoxide resin and aliquid accelerator

100 g of the epoxide resin according to Example 1 are weighed togetherwith 50 g of the accelerator according to Example 3 into a tinplate box,at room temperature, and mixed with a paddle stirrer. 128 g of quartzpowder, 106 g of extremely fine quartz powder and 16 g of syntheticcalcium silicate (xonotlite) are then weighed in and the whole is mixedfor about 1 minute at 1,300 rpm at room temperature. A pulverulentproduct containing small crumbs results.

The mixture is stable on storage for about 1 month.

EXAMPLE 5

Preparation of a pourable, curable epoxide resin mixture from liquidreactants.

100 g of the mixture according to Example 4 and 80 g of phthalicanhydride are weighed together at room temperature into a tinplate boxand mixed for 1 minute at 1,300 rpm with a paddle stirrer.

Pourable crumbs 2 to 3 mm in diameter form. The entire contents can beemptied out by simply pouring out.

The pourable, curable mixture is stable on storage for about 1 month.

APPLICATION EXAMPLES EXAMPLE 6

The pourable epoxide resin according to Example 1 is weighed into atinplate box and warmed to 100° C. on a hotplate, with stirring, and thecuring agent and accelerator which have been mentioned in Examples 2 and3 respectively and which have been pre-warmed to 60° C. are then added,with stirring. The system is then homogenised using a paddle stirrerand, at 80° C., poured into moulds and cured (viscosity at 80° C.: 7,000to 10,000 mPas).

In a second test, the pourable resin component is brought to the desiredtemperature in a drying cabinet before the curing agent is added. Themixing operation remains unchanged.

EXAMPLE 7

The pourable curing agent according to Example 2 is weighed into atinplate box and warmed to 100° C. on a hotplate, with stirring, and aliquid epoxide resin (epoxide resin based on bisphenol A with 8.6 partsby weight of butylene glycol diglycidyl ether, epoxide content about 5.5equivalents/kg), which has been pre-warmed to about 60° C., and theaccelerator (as mentioned in Example 3) are then added, with stirring.The system is then homogenised using a paddle stirrer and, at 80° C.,poured into moulds and cured (viscosity at 80° C.: 14,000 to 17,000mPas).

If desired, in this case also, the pourable curing component can bebrought to the desired temperature in a drying cabinet.

EXAMPLE 8

The filled resin/accelerator mixture according to Example 4 is weighedinto a tinplate box and warmed to about 100° C. on a hotplate, withstirring, and the hexahydrophthalic anhydride curing agent, which hasbeen prewarmed to 60° C., is then added, with stirring.

The mixture is then homogenised using a paddle stirrer and, at 80° C.,poured into moulds and cured.

EXAMPLE 9

The required amount of the pourable mixture according to Example 5 isweighed into a tinplate box, melted on a hotplate, with stirring, andhomogenised, in order then to be poured at 110° C. to 120° C. intomoulds and cured.

EXAMPLE 10 Epoxide resin system filled with chalk powder

100 parts by weight of an epoxide resin which has been prepared frombisphenol A and epichlorohydrin and has an epoxide content of 5.3equivalents per kg are mixed with 330 parts by weight of chalk powder(62.26%, based on the subsequent total mixture) and 0.5 part by weightof XONOTILT VP 633 to 330 (from Quarzwerke Frechen, Federal Republic ofGermany) in a stainless steel vessel, using a turbostirrer at 3,000revolutions per minute, in the course of 2 minutes to give pourable,non-dusting granules. The granules can be stored in plastic bags withoutwetting the film surface.

To prepare a castable mixture, 100 parts by weight of modified anhydridecuring agent are warmed to 120° C. in a vessel fitted with a stirrer,and the pourable granules are added rapidly and, then, 0.2 part byweight of an anionic accelerator is added. For the production ofmouldings, the casting resin mixture is poured, while still hot, intomoulds and cured.

EXAMPLE 11 Flame-retardant casting resin system containing Al₂ O₃.3H₂ O

100 parts by weight of an epoxide resin which has been prepared frombisphenol A and epichlorohydrin and has an epoxide content of 5.2equivalents per kg and 100 parts by weight of Sikron quartz powder, 170parts by weight of aluminium oxide trihydrate and 0.5 part by weight ofXONOTILT VP 633-330 are converted, in a stainless steel vessel, using aturbostirrer at 3,000 revolutions per minute, in the course of 2 minutesinto pourable, dry, non-caking granules. This filled, dry resin mixtureis added to 80 parts by weight of a modified anhydride curing agent,which has been pre-warmed to 80° C., with stirring, and activated with0.2 part by weight of an anionic accelerator. The resulting castingresin mixture, which is at about 60° C., can be poured into moulds.After curing the mixture for 16 hours at 130° C., flame-retardantmouldings are obtained (UL-V-O).

What is claimed is:
 1. A pourable, solid mixture which contains, basedon the total mixture,(a) 49.75 to 7.5% by weight of a liquid syntheticresin which is an epoxide resin, unsaturated polyester resin,polyurethane resin, phenol/formaldehyde resin, urea/formaldehyde resin,melamine/formaldehyde resin, oil-modified alkyd resin, polysilicone orunsaturated polyimide, (b) 50 to 87.5% by weight of a mineral filler,and (c) 0.25 to 5% by weight of a crystalline synthetic calciumsilicate, which can be in diverse stages of hydration and has a highlength/width ratio and a width dimension of less than 1 μm.
 2. A mixtureaccording to claim 1, which contains component (a) in a proportion of35-15% by weight and component (b) in a proportion of 65-85% by weight.3. A mixture according to claim 1, wherein the mineral filler is quartzpowder, mica, talc, asbestos, slate flour, kaolin, wollastonite,powdered chalk, dolomite, magnesium carbonate, gypsum, barytes,aluminium oxide, bentones, silicic acid aerogel, lithopones, titaniumdioxide, carbon black, graphite, metal oxides, glass powders, glassspheres, glass fibres, zinc sulfide, silicon carbide, cristoballite or amixture of fillers.
 4. A mixture according to claim 1, wherein thecalcium silicate has a length/width ratio in the range from 10:1 to200:1.
 5. A mixture according to claim 1, wherein the calcium silicateis acicular crystallised xonotlite of the formula Ca₆ [(OH)₂ /Si₆ O₁₇ ].6. A process for the preparation of a pourable, solid mixture accordingto claim 1 which comprisesadding components (a), (b) and (c) to astirred vessel, and stirring the resulting mixture to disperse thecalcium silicate, component (c), homogeneously therein and to convertthe mixture into a solid, dry pourable material.
 7. A pourable, solidmixture which contains, based on the total mixture,(a) 49.75 to 7.5% byweight of a liquid which is a combination of a liquid epoxy resin and aliquid curing agent therefor; or is a liquid epoxy resin whichadditionally contains a finely divided solid curing agent therefor; oris a liquid curing agent which additionally contains a finely dividedsolid epoxy resin curable therewith, (b) 50 to 87.5% by weight of amineral filler, and (c) 0.25 to 5% by weight of a crystalline syntheticcalcium silicate, which can be in diverse stages of hydration and has ahigh length/width ratio and a width dimension of less than 1 μm.
 8. Amixture according to claim 7 which contains component (a) in aproportion of 35-15% by weight and component (b) in a proportion of65-85% by weight.
 9. A mixture according to claim 7, wherein the mineralfiller is quartz powder, mica, talc, asbestos, slate flour, kaolin,wollastonite, powdered chalk, dolomite, magnesium carbonate, gypsum,barytes, aluminium oxide, bentones, silicic acid aerogel, lithopones,titanium dioxide, carbon black, graphite, metal oxides, glass powders,glass spheres, glass fibres, zinc sulfide, silicon carbide,cristoballite or a mixture of fillers.
 10. A mixture according to claim7, wherein the calcium silicate has a length/width ratio in the rangefrom 10:1 to 200:1.
 11. A mixture according to claim 7, wherein thecalcium silicate is acicular crystallised xonotlite of the formula Ca₆[(OH)₂ /Si₆ O₁₇ ].
 12. A process for the preparation of a pourable,solid mixture according to claim 7 which comprisesadding components (a),(b) and (c) to a stirred vessel, and stirring the resulting mixture todisperse the calcium silicate, component (c), homogeneously therein andto convert the mixture into a solid, dry pourable material.